Apparatus for well completion



Oct. 24, 1967 N. A. SCH USTER APPARATUS FOR WELL COMPLETION Originai Filed April 29, 1955 S Sheets-Sheet 1 a? 3 15 aawawvwwa ya a a; a 33 Wm H m. H J V v T. m A C n A A m. m I m 3 (III I l 1 l i IM I m ,1967 N. A. SCHUSTER 3,348,621

APPARATUS FOR WELL COMPLETION Original Filed April 29, 1965 .3 Sheets-Sheet 2 2 I I, I INVENTORi /fl mz O 1967 N. A. SCHUSTER APPARATUS FOR WELL COMPLETION Original Fiied April 29, 1965 3 Sheets-Sheet 5 INVENTOR.

States atent 3,348,621 Patented Oct. 24, 1967 ice 9 Claims. or. 175-452 ABSTRACT OF THE DISCLOSURE This application discloses well-completion apparatus for injecting fluids into earth formations. More particularly, the disclosed apparatus includes appropriately arranged sealing members adapted for isolating a wall of a Well bore and two or more spaced perforating devices adapted to perforate spaced portions of an isolated well bore wall and form a circuitous flow passage in the formation. Fluid-discharge means are arranged in the apparatus for injecting selected fluent agents such as, for example, formation-consolidating materials into the flow passages through one of these isolated portions either in conjunction with or subsequent to the withdrawal of loosened debris and the like in the passages by way of the other isolated portion. The debris is withdrawn from the aforesaid flow passages and through the other isolated portion and received in an enclosed chamber on the apparatus which is opened upon command from the surface.

This application is a division of application Ser. No. 451,787 filed Apr. 29, 1965.

Accordingly, as will be subsequently apparent, this invention relates to apparatus for completing wells; and, more particularly, to apparatus for inhibiting the production of sand from unconsolidated or incompetent subsurface formations.

The present trend in well-completion techniques is to rely upon only one or, at most, a very few perforations at each of carefully selected points in a well rather than indiscriminately scattering a larger number of perforations along a wide interval. Where such perforations are made into a particularly loose or unconsolidated formation, sand particles and the like, will, however, be displaced into the well bore as connate fluids are produced from the formation. Thus, unless preventative measures are taken, these sand particles will either settle out and eventually fill the well bore or be carried to the surface by the produced fluids and severely damage production equipment. Moreover, with only a few perforations affording limited entry into the formation, the production will be severely limited should any of these perforations become plugged.

Accordingly, to solve these problems, apparatus and methods have been devised whereby as soon as a loose formation is perforated, a suitable bonding or consolidating agent is injected through the perforation into the formation where, in time, it will react and harden. These agents or so-called plastics generally coat the sand particles and thereby cement them together. Although it will depend upon the particular agents employed, the pore spaces between adjacent particles are left open in one way or another so as to provide permeability. Thus, a portion of the formation surrounding the perforation is consolidated to serve as a porous support to prevent loose sand particles from entering the perforation as connate fluids are produced from the formation.

Typical of such treating agents, apparatus and methods are those disclosed in Patents Nos. 3,153,449, granted to Maurice P. Lebourg, and 3,174,547, granted to Roger Q. Fields. As described in those patents, a perforating-andinjection tool is positioned adjacent a formation that is believed to be unconsolidated. An extendible wall-engaging member is operated to shift the tool toward one wall of the casing and sealingly engage a sealing member on the opposite wall to isolate a portion of the well bore from the well control fluids. A perforator, such as a shaped charge, is then actuated to produce a perforation through the isolated portion into the adjacent earth formations.

Thereafter, a bonding agent is ejected from a cylinder in the tool by a displacing piston and ejected through the perforation into the formation.

The present invention is directed toward providing new and improved apparatus for injecting formation-consolidating materials into unconsolidated formation. In employing this apparatus, shaped charges are detonated to produce a circuitous flow passage within the formation. When the shaped charges are detonated, however, they will deposit low-permeability debris within the perforations and on their walls. Examinations have shown that this low-permeability debris includes casing and cement particles as well as residue products of the shaped charges.

Thus, with the apparatus of the present invention, after the shaped charges are detonated, fluid communication is established through the circuitous flow passage between a low-pressure receiver and a source of treating agents at the hydrostatic pressure of the well control fluids. Connate fluids and the treating agents will then flush the debris from the flow passage into the receiver. When the receiver is filled, the formation-consolidating agent is injected through the cleaned passage into the formation.

Accordingly, it is an object of the present invention to provide new and improved apparatus for obtaining flow passages into earth formations that are free of such objectionable low-permeability debris to increase the flow rate at which treating agents can be injected into the for mations as well as the flow rate at which connate fluids may be subsequently produced.

This and other objects of the present invention are provided with apparatus comprised of packing means that are selectively operable to isolate adjacent surfaces of an earth formation and cooperatively arranged with perforating means for producing a circuitous flow passage through the formation from one surface to another as well as means for withdrawing debris from the passage either before or concurrently with the injection of treating agents into the passage.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a view of one embodiment of a well-compleltion tool arranged in accordance with the present invention within a well bore and in position to consolidate an earth formation;

FIG. 2 is an elevational view, partially in cross-section, of a portion of the tool depicted in FIG. 1;

FIGS. 3-5 are views depicting in sequence the apparatus of FIG. 1 performing a formation-consolidating operation; and

FIGS. 6-8 are views depicting in sequence apparatus similar to that shown in FIG. 1 but practicing a different procedure for consolidating an earth formation.

Turning now to FIG. 1, a well-completion tool 10* employing the principles of the present invention is shown suspended from a multi-conductor cable 11 in a casing 12 secured within a borehole 13 by a column of cement 14. The cable 11 is spooled from a winch (not shown) at the earths surface, with some of its conductors being arranged for selective connection to a conventional power source (not shown) and others being connected to conventional mdicating-and-recording means (not shown) at the surface of the ground.

The well-completion tool is comprised of an elongated body 15 which, to facilitate manufacture and assembly, may be arranged in tandemly connected sections. Longitudinally spaced, annular pack-off means or sealing members 16 and 1-7 are disposed on one side of the body 15 and extendible and retractable wall-engaging means 18 on its opposite side.

The upper portion of the body 15 encloses a hydraulic system (not shown) for selectively actuating the extendible wall-engaging means 18. This hydraulic system may, for example, be of the type illustrated in Patent No. 3,011,554, granted to Robert Desbrandes, which utilizes the hydrostatic pressure of the well control fluids or mud 19 to develop an increased pressure in the system for selectively actuating the wall-engaging means 18. Thus, upon command from the surface, the wall-engaging means 18 will be extended against one side of the casing 12 to shift the tool 10 laterally and sealingly engage the sealing members 16 and 17 against the opposite side of the casing.

The hydraulically actuated wall-engaging means 18 are comprised of one or more extendible pistons 20 that support a back-up shoe 21 that is normally held in a retracted position against the body 15 by springs 22. The pistons 20 are sealingly received within hydraulic cylinders (not shown) that are connected to the hydraulic system. Thus, whenever the hydraulic system is activated from the surface, the developed hydraulic pressure will urge the pistons 20 outwardly to extend the back-up shoe 21 against the casing 12. Subsequently, the hydraulic system can be de-activated to relieve the hydraulic pressure in the pistons so that retraction of the shoe 21 can be effected. Inasmuch as the particular details of the hydraulic system and wall-engaging means 18 are not necessary for fully understanding the present invention, they have been shown only schematically in FIG. 1 to show their general relationship to the present invention.

Separate treating-agent cylinders 23 and 24 are formed in the lower portion of the body 15 which may, for example, be arranged as disclosed in the aforementioned Lebourg and Fields patents. Thus, as described in the Fields patent, the upper cylinder 23 sealingly receives a slidable, annular, piston member 25 that is sealingly engaged around a concentrically positioned tubular member 26 that extends through the upper cylinder into the lower cylinder 24. The upper cylinder 23 is connected by a centrally located passage 27 to a normally-closed valve 28, such as that shown at 41 in Patent No. 3,121,459. A port 29 is provided below the annular piston member 25 so that well control fluids 19 can act upon the piston to displace a treating agent from the cylinder 23 through passage 27 whenever the valve 28 is opened.

The lower cylinder 24 is divided into separate compartments 30-32 by spaced, floating pistons 33-35 that are each fluidly sealed to the inner wall of the cylinder. As will be subsequently explained in greater detail, normally-closed valves 36 and 37 in the floating pistons 33 and 34 remain closed to segregate the treating agents in the chambers 30-32 until each piston has reached its upper limit of travel. These pistons 33 and 34 and valves 36 and 37 may be, for example, of the type illustrated in FIG. 3 of the aforementioned Fields patent. A port 38 in the lower end of the cylinder 24 admits well control fluids 19 into the space below the lower piston 35. Thus, as described in greater detail in the Fields patent, the hydrostatic pressure of the well control fluids 19 acting on the lower piston will exert pressure on the treating agents in the chambers 30 32 to sequentially discharge the treating agents from the chambers through the tubular member 26 and into a fluid passage 39 thereabove which has a normally-open valve 40, such as at 165, in the above-mentioned Desbrandes patent.

The passages 27 and 39 converge above their respective valves 28 and 40 and are connected to a fluid passage 41 leading to the fluid discharge means 42 of the present invention. A pressure transducer 43 is provided to continuously :monitor the pressure in the fluid passage 41. This transducer 43 may, for example, be of the type shown in FIG. 9 of the Desbrandes patent and is connected by an electrical lead (not shown) via the cable 11 to the pressure indicating-and-recording apparatus at the surface of the earth. Thus, by observing the variations in pressure measurements, an operator can determine the occurrence of various functions of the operating cycle of the well-completion tool 10'.

The fluid discharge means 42 of the present invention include a pair of lateral chambers 44 and 45 within the body 15 that are each open at one end, with the annular sealing members 16 and 17 being mounted around the open ends of these chambers to provide central openings 46 and 47. The lower chamber 45 is connected to fluid passage 41; and thin-walled closure members 48 and 49 are mounted in the chamber on each side of the open upper end of the passage to block the central opening 47 and the rearward portion of the chamber. A shaped charge 50 is received in the rearward portion of the chamber 45 and faces the closure members 48 and 49 so that, upon detonation, the perforating jet will puncture the closure members and be directed through the central opening 47.

In a similar manner, the upper chamber 44 is connected by a fluid passage 51 to an enclosed low-pressure or atmospheric chamber 52 in the body 15. Thin-walled closure members 53 and 54 are mounted in the upper chamber 44 on each side of the open lower end of the passage 51 to block the central opening 46 of the sealing member 16 and the rearward portion of the chamber. A shaped charge 55 is dispose-d in the rear of the chamber 44 and directed toward the closure members 53 and 54 so that, upon detonation, the perforating jet will pierce the closure members and be directed through the central opening 46. Suitable electrically responsive igniter means 56 and 57 (FIG. 2) that are ignitable from the surface of the earth via conductors in the cable 11, are connected to the shaped charges 55 and 50.

It will be realized that when the shaped charge 50 is detonated to puncture the closure members 48 and 49 and produce a perforation into an earth formation, fluid communication will be established from the fluid passage 41 through the central opening 47 and into the resultant perforation. Similarly, whenever the other shaped charge 55 is detonated, the closure members 53 and 54 will be pierced and fluid communication will be established from the resultant perforation through the central opening 46 and into the low-pressure chamber 52. Accordingly, by detonating the shaped charges 50 and 55, a circuitous passage (FIG. 3) will be produced in an adjacent earth formation that extends between the central openings 46 and 47. Thus, debris that is deposited in the circuitous passage can be swept into the low-pressure chamber 52 and treating agents may be injected into the fluid passage either concurrently or shortly thereafter.

Turning now to FIG. 2, an elevational view, partially in cross-section, is shown of a preferred embodiment of the fluid discharge means 42, with reference numerals used in conjunction with FIG. 1 identifying the corresponding elements. The shaped charge chambers 44 and 45 are formed in the body 15 by longitudinally spaced lateral bores that are tilted in such a manner that their central axes 58 and 59 intersect a short distance in front of the forward ends of the bores. The shaped charges 50 and 55 are secured and fluidly sealed in their chambers 45 and 44 behind threaded tubular members 60 and 61 having enlarged-diameter flanges 62 and 63 on their forward ends. The flanges 62 and 63 support metal back plates 64 and 65 carrying the elastomeric sealing members 16 and 17 and are recived within forwardly facing counterbores 66 and 67 in the body and fluidly sealed therein by O-rings 68 and 69. O-rings 70 and 71 around the central portions of the tubular members 60 and 61 provide fluid-tight annular spaces 72 and 73 in the forward ends of the lateral chambers 45 and 44, with radial bores 74 and 75 connecting these spaces to the central bores through the tubular members.

The thin-walled closure members 53 and 54 are spaced apart and threadedly secured in the central bore through the upper tubular member 61 on opposite sides of the radial bores 75 to block the central opening 46 and isolate the shaped charge 55. The fluid passage 51 connects the space between the thin-walled closure members 53 and 54 to an enlarged bore thereabove that is closed at its upper end to provide the atmospheric chamber 52. To detonate the shaped charge 55, detonating means 56 are comprised of a short length of detonating cord 76 disposed on the rear of the shaped charge and coupled to a conventional electrical detonator 77 received within a transverse passage 78 extending upwardly from the shaped charge chamber 14.

The other thin-walled closure members 48 and 49 are arranged in the same manner and define a space therebetween in the central bore of the lower tubular member 60 that is connected by the radial bores 74 to the main fluid passage 41. The shaped charge 50 is detonated by detonating means 57 comprised of a detonating cord 79 and electrical detonator 80. The hydraulically actuated pistons are mounted in hydraulic cylinders in the body 15 with the back-up shoe 21 being normally retracted against the rear face of the body.

Turning now to FIGS. 3-5, the successive steps of operation of the well-completion tool 10 are depicted. Although the exact arrangement will be determined by the particular consolidating materials to be used, a pre-fiush fluid 81, such as a saline solution, is contained inthe upper chamber of the lower treating cylinder 24. The intermediate chamber 31 contains a plastic consolidation agent 82, such as a formaline-cresol mixture, while the lower chamber 32 contains an after-flush agent 83, such as kerosene. A suitable temporary plugging agent 84, such as Black Magic oil-base mud as supplied by Oil Base, Inc., of Compton, Calif, is deposited in the upper treating cylinder 23.

After the treating agents 8184 have been deposited in the cylinders 23 and 24, the tool 10 is assembled and positioned in a well bore 13 adjacent a selected forma tion 85. By actuating the hydraulic system, the back-up shoe 21 is extended to shift the tool 10 laterally and sealingly engage the sealing members 16 and 17 against the casing 12. Once the sealing members 16 and 17 have been firmly seated, it will be appreciated that the central openings 46 and 47 in front of the thin-walled closure members 54 and 49 will be isolated from the well control fluids 19 in the well bore 13. By this time, the hydrostatic pressure of the well control fluids 19 will have displaced some of the pre-flush fluid 81 from the upper chamber 30 through the normally-open valve 39 and into the space between the thin-walled closure members 53 and 54.

The lower shaped charge 50 is then detonated to puncture the thin-walled closure members 53 and 54 and produce a perforation 86 that is directed into the formation 85 in a slightly upward direction. As the perforating jet punctures the closure member 54, the hydrostatic pressure of the well control fluids 19 (which are at a higher pressure than the formation fluids) will immediately displace pre-flush fluid 81 into the perforation 86. Then, as best seen in FIG. 3, when the other shaped charge 55 is detonated to produce a second perforation 87 that either intersects the first perforation 86 or comes in close proximity thereto, flow communications will be established through the second perforation from the first perforation to the atmospheric chamber 52. Thus, by suddenly opening communications from the formation to the atmospheric chamber 52, the formation pressure will displace connate fluids and adjacent sand particles into the perforations 86 and 87 and on into the atmospheric chamber along with the per-flush fluid 81. This sudden in-rush of the fluids will flush the debris from within the perforations. It will be appreciated that the sudden in-rush of the pre-flush fluid 81 may enlarge the perforations 86 and 87, as at 88 to provide a still greater surface area for admitting other treating agents. Chamber 52 is preferably of less volume than the volume of the upper chamber 30 for the pre-flush fluid 81.

Thus, as best seen in FIG. 4, once the pre-flush fluid 81 has been expelled from the upper chamber 30, the upper floating piston 33 will have reached the top of the cylinder 24 to open the valve 36 therein. Then, the continued application of hydrostatic pressure on the lower piston 35 will displace the other treating agents 82 and 83 in controlled sequence from the intermediate and lower chambers 31 and 32 into the formation 85 where the consolidating plastic agent 82 will harden and, in time, consolidate the loose formation.

It should be understood that the detonation of the second shaped charge 55 and opening of the formations to the low-pressure chamber 52 causes both the formation fluids and pressurized pre-flush agent 81 to flush any debris from the perforations. This flushing action which is precipitated by detonation of the second shaped charge 55 can be at any selected time during injection so long as the injection fluids are viscous enough to effect the desired removal of the aforementioned debris.

After closing the normally-open valve 40' by command from the surface, the normally-closed valve 28 is then opened. The hydrostatic pressure of the well control fluids 19 acting through the port 29 will then urge the annular piston 25 upwardly to displace the temporary plugging agent 84 from the upper cylinder 23 into the perforations 86 and 87 or cavity 88. Agent 84 by filtration builds up a relatively impermeable surface which prevents contact of the well control fluids with plastics in the cavity 88 when the pack-off means 16 and 17 are removed.

Once all of the treating agents 81-84 have been expelled from the tool 10, the hydraulic system is actuated to relieve the hydraulic pressure therein to retract the backup shoe 21 and allow the tool to be withdrawn from the well bore 13. The pressure of the well control fluids 19 maintains the temporary plugging agent 84 in the cavity 88 while the plastic is setting.

:Turning now to FIGS. 68, a well-completion tool is shown that is similar to the tool 10 but is capable of perforating a further operational function. Inasmuch as the well-completion tool 100 may be arranged in the same manner as the well completion tool 10 but with only minor additions, the same reference numerals employed in FIGS. 1-3 have been used in FIGS. 68 with prime marks thereafter to designate the equivalent elements and simplify the description of tool 100. Accordingly, it will be appreciated by comparison of the two groups of figures that well-completion tool 100 differs essentially from wellcompletion tool 10 only in that a second atmospheric chamber 101 is provided that is connected to atmospheric chamber 52' by way of a fluid passage 102 that is closed by a selectively-operable, normally-closed valve 103.

After treating agents 8184' have been deposited in the chambers 23' and 24', the tool 100 is assembled and positioned in a well bore 104 as seen in FIG. 6 adjacent a selected formation 105. By actuating the hydraulic system, the back-up shoe 21' is extended to shift the tool 100 laterally and sealingly engage the sealing members 16' and 17' against the casing 106. Once the sealing members 16' and 17' have been firmly seated, it will be appreciated that the central openings in front of the thin-walled closure members 49' and 54' will be isolated from the well control fluids 107 in the well bore 104. At this time, the hydrostatic pressure of the well control fluids 107 will have displaced some of the pre-flush fluids 81' from the upper chamber through the normallyopen valve and into the space between the thin-walled closure members 48 and 49.

The lower shaped charge 50' is then detonated to puncture the thin-walled closure members 48 and 49' and produce a perforation 108 that is directed into the formation 105 in a slightly upward direction. As the perforating jet punctures the closure member 49, the hydrostatic pressure of the well control fluids 107 (which are at a higher pressure than the formation fluids) will immediately displace pre-flush fluid 81 into the perforation 108. Then, when the other shaped charge is detonated to provide a second perforation 109 that either intersects the first perforation 108 or comes in close proximity thereto, fluid communication will be established through the second perforation from the first perforation to the atmospheric chamber 52'. Thus, by suddenly opening communication from the formation 105 to the atmospheric chamber 52, the formation pressure will displace connate fluids and adjacent sand particles into the perforations 108, 109 and on into the atmospheric chamber 52 along with the pre-flush fluid 81'. This sudden in-rush of fluids will flush the debris from within the perforations. It will be appreciated that the sudden in-rush of the preflush fluid 81' may enlarge the perforations 108 and 109, as at 110, to provide a still greater surface area for admission of treating agents.

Thus, as best seen in FIG. 7, once the pre-flush fluid 81' has been expelled from the upper chamber 30, the upper floating piston 33 will have reached the top of the cylinder 24 to open the valve 36. Then, the continued application of the hydrostatic pressure on piston 35 will inject the other treating agents 82' and 83' in controlled sequence from the intermediate and lower chambers 31' and 32 and into the formation 105 where, in time, the consolidating plastic agent 82' will harden and consolidate the loose formation. Then, when the treating agents 82' and 83' have been exhausted, valve 40 may be closed if desired and valve 28' opened. Opening of valve 28' will admit the plugging agent 84 into the cavity 110 and allow it to infiltrate the formation 105 until a relatively impermeable filtrate layer has been built up on the cavity walls.

To prevent collapse of the cavity 110, which might occur because of formation pressure equalization or of substantial overburden pressures in a particularly unconsolidated formation, as seen in FIG. 8, a valve 103 is then opened by command from the surface to exhaust the contents of chamber 52' into the other atmospheric chamber 101. This sudden exhausting of the contents of chamber 52' will, of course, allow a quantity of the plugging agent 84' to flow through the cavity 110 and into the chamber 52. The flow of this final flushing will be maintained by hydrostatic pressure and the plugging agent 84' will again form an impermeable filtrate layer. When the tool is removed, the hydrostatic pressure acting on the plugging agent 84 in the cavity 110 will support the cavity and prevent well control fluids 107 from invading the formation 105. It should be understood, of course, that a valve, such as at 103, could also be used to control fluid communication through passage 51' (and passage 51 in FIG. 1).

Once all of the treating agents 81-84 have been expelled from the tool 100, the hydraulic system is actuated to relieve the hydraulic pressure therein to retract the back-up shoe 21' and allow the tool to be withdrawn from the well bore 104. After the porous support 111 about the cavity 110 has hardened, the pressure of the control fluids 19 can be removed and production can be commenced. The pressure of formation fluids when greater than the pressure within the casing, causes the temporary plugging agent to be displaced into the casing 12.

Thus, it will be appreciated that the present invention has provided new and improved apparatus for obtaining fluid passages into earth formations that are free of objectionable low-permeability debris so that materials may be injected into the formations at reasonably high flow rates. It should be noted that although the foregoing description was primarily directed to the application of the apparatus of the present invention in sand consolidation operations, such apparatus will be equally successful in other completion operations where it is desired to inject flowable materials into an earth formation at reasonably high flow rates.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects; and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. Apparatus for use in a well bore traversing earth formations comprising: a support; sealing means on said support adapted for isolating first and second sections of a well bore from fluids in a well bore; means on said support for placing said sealing means into sealing engagement with a well bore; first and second perforating means on said support isolated from one another and adapted, upon operation, for passing through said sealing means and producing first and second perforations in an earth formation respectively in communication with such isolated sections; means on said support for discharging fluid under pressure through one of such isolated sections into one of such perforations; and means on said support for receiving fluid through the other of such isolated sections from the other of such perforations for removing debris therefrom.

2. The apparatus of claim 1 wherein said first and second perforating means are adapted to produce perforations approaching an intersection with one another.

3. The apparatus of claim 1 further including: an opening in said sealing means aligned with said first perforating means and in communication with said fluiddischarging means; and closure means normally closing said opening and adapted for perforation by said first perforating means.

4. The apparatus of claim 1 further including: an opening in saidsealing means aligned with said first perforating means and in communication with said fluidreceiving means; and closure means normally closing said opening and adapted for perforation by said first perforating means.

5. The apparatus of claim 4 further including: an enclosed chamber on said support and in communication with said fluid-receiving means; and means blocking fluid communication between said enclosed chamber and said fluid-receiving means and selectively operable for opening such fluid communication.

6. The apparatus of claim 4 further including: a second opening in said sealing means aligned with said second perforating means and in fluid communication with said fluid-discharging means; and second closure means normally closing said second opening and adapted for perforation by said second perforating means.

7. The apparatus of claim 5 further including: a second opening in said sealing means aligned with said second perforating means and in fluid communication with said fluid-discharging means; and second closure means normally closing said second opening and adapted for perforation upon operation of said second perforating means and producing a second perforation in an earth formation adjacent to said second opening.

8. The apparatus of claim 7 further including: an enclosed chamber on said support and in communication with said fluid-receiving means; and means normally blocking fluid communication between said enclosed chamber and said fluid-receiving means and selectively operable for opening such fluid communication.

9. Apparatus for use in a well bore traversing earth formations comprising: a support having first and second lateral chambers, each chamber having an open end and a closure member closing said open chamber end; perforating means mounted in each of said chambers and directed toward said closure member for perforating said closure member, upon operation, and producing a perforation in an earth formation; sealing means on said support around said open chamber ends and adapted for isolating first and second well surfaces of a well bore adjacent to said open chamber ends from fluids in a well bore; means on said support for placing said sealing means into engagement with a wall of a well bore; means UNITED STATES PATENTS 2,821,256 1/1958 Boller 166100 X 3,121,459 2/1964 Van Ness et a1. 1663 3,174,547 3/1965 Fields 166100 X 3,273,647 9/1966 Briggs et a1. 166100 3,273,659 9/1966 Reynolds 166100 3,318,381 5/1967 Brandt 16635 CHARLES E. OCONNELL, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,348,621 October 24, 1967 Nick A. Schuster It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 17, for "formation" read formations column 5, line 5, for "recived" read received line 26, for "14" read 44 column 8, line 56, for "blocking" read normally blocking lines 72 and 73 strike out "and producing a second perforation in an earth formation adjacent to said second opening Signed and sealed this 15th day of April 1969.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer 

1. APPARATUS FOR USE IN A WELL BORE TRAVERSING EARTH FORMATIONS COMPRISING: A SUPPORT; SEALING MEANS ON SAID SUPPORT ADAPTED FOR ISOLATING FIRST AND SECOND SECTIONS OF A WELL BORE FROM FLUIDS IN A WELL BORE; MEANS ON SAID SUPPORT FOR PLACING SAID SEALING MEANS INTO SEALING ENGAGEMENT WITH A WELL BORE; FIRST AND SECOND PERFORATING MEANS ON SAID SUPPORT ISOLATED FROM ONE ANOTHER AND ADAPTED, UPON OPERATION, FOR PASSING THROUGH SAID SEALING MEANS AND PRODUCING FIRST AND SECOND PERFORATIONS IN AN EARTH FORMATION RESPECTIVELY IN COMMUNICATION WITH SUCH ISOLATED SECTIONS; MEANS ON SUPPORT FOR DISCHARGING FLUID UNDER PRESSURE THROUGH ONE OF SUCH ISOLATED SECTIONS INTO ONE OF SUCH PERFORATIONS; AND MEANS ON SAID SUPPORT FOR RECEIVING FLUID THROUGH THE OTHER OF SUCH 